Pandemic clue from 1918 virus

A key protein isolated by researchers in an experiment on mice has been shown to worsen the effect of influenza viruses, making secondary bacterial infections more likely and increasing mortality.

The clue lies in the virus which caused more than 40 million deaths in the 1918 "Spanish flu" pandemic, which is often called the worst pandemic in human history.

A new study published in the mircrobiology journal Cell & Microbe has revealed important information about that virus' genetic make-up which could provide clues about how to prepare for future pandemics.

The 1918 pandemic flu strain was highly virulent, and actually capable of killing healthy human victims on its own. However, a large proportion of the recorded deaths are believed to have been the result of secondary infection by bacteria, leading to pneumonia.

The way in which influenza and bacteria interact is still a largely uncharted area for research.

A research team led by Jonathan A McCullers of St. Jude Children's Research Hospital in Memphis, Tennessee managed to identify a protein known as PB1-F2, which is present in all influenza A viruses, and show that it made the effects of the infection far worse in mice.

Specifically, it seemed to make the mice sicker and more likely to die, because they were contracting secondary pneumonia; a bacterial, rather than a viral, infection.

The presence of the protein is believed to explain the unparalleled virulence of the 1918 influenza strain and the high incidence of fatal pneumonia during the pandemic.

The results of the study back up suggestions already made by experts that governments should stockpile antibiotics as well as oseltamivir (Tamiflu) in preparation for the next pandemic.

Nearly 300 people worldwide have caught bird flu, caused by the H5N1 avian influenza virus, almost certainly from contact with sick poultry, since 2003 and more than half of them have died.

The H5N1 virus has ripped through poultry flocks in Asia and Africa, with millions of birds culled.

While the virus is a version of the influenza A virus, it is different from seasonal influenza, where infection ranges from mild to serious symptoms in most people.

In humans H5N1 is far more severe and happens quickly, with pneumonia and multiple organ failure commonly seen. Experts fear it could mutate to a form easily transmissible between humans, sparking the next pandemic and killing millions globally.